Hu Shunying, Zhu Pingjun, Zhou Hao, Zhang Ying, Chen Yundai
Chinese PLA General Hospital, Beijing - China.
Arq Bras Cardiol. 2018 Jan;110(1):44-51. doi: 10.5935/abc.20180008.
Melatonin is a neuroendocrine hormone synthesized primarily by the pineal gland that is indicated to effectively prevent myocardial reperfusion injury. It is unclear whether melatonin protects cardiac function from reperfusion injury by modulating intracellular calcium homeostasis.
Demonstrate that melatonin protect against myocardial reperfusion injury through modulating IP3R and SERCA2a to maintain calcium homeostasis via activation of ERK1 in cardiomyocytes.
In vitro experiments were performed using H9C2 cells undergoing simulative hypoxia/reoxygenation (H/R) induction. Expression level of ERK1, IP3R and SERCA2a were assessed by Western Blots. Cardiomyocytes apoptosis was detected by TUNEL. Phalloidin-staining was used to assess alteration of actin filament organization of cardiomyocytes. Fura-2 /AM was used to measure intracellular Ca2+ concentration. Performing in vivo experiments, myocardial expression of IP3R and SERCA2a were detected by immunofluorescence staining using myocardial ischemia/ reperfusion (I/R) model in rats.
In vitro results showed that melatonin induces ERK1 activation in cardiomyocytes against H/R which was inhibited by PD98059 (ERK1 inhibitor). The results showed melatonin inhibit apoptosis of cardiomyocytes and improve actin filament organization in cardiomyocytes against H/R, because both could be reversed by PD98059. Melatonin was showed to reduce calcium overload, further to inhibit IP3R expression and promote SERCA2a expression via ERK1 pathway in cardiomyocytes against H/R. Melatonin induced lower IP3R and higher SERCA2a expression in myocardium that were reversed by PD98059.
melatonin-induced cardioprotection against reperfusion injury is at least partly through modulation of IP3R and SERCA2a to maintain intracellular calcium homeostasis via activation of ERK1.
褪黑素是一种主要由松果体合成的神经内分泌激素，已表明其能有效预防心肌再灌注损伤。目前尚不清楚褪黑素是否通过调节细胞内钙稳态来保护心脏功能免受再灌注损伤。
证明褪黑素通过调节肌醇三磷酸受体（IP3R）和肌浆网钙ATP酶2a（SERCA2a），经激活心肌细胞中的细胞外信号调节激酶1（ERK1）来维持钙稳态，从而预防心肌再灌注损伤。
使用经历模拟缺氧/复氧（H/R）诱导的H9C2细胞进行体外实验。通过蛋白质免疫印迹法评估ERK1、IP3R和SERCA2a的表达水平。采用末端脱氧核苷酸转移酶介导的缺口末端标记法（TUNEL）检测心肌细胞凋亡。用鬼笔环肽染色评估心肌细胞肌动蛋白丝组织的改变。用Fura-2/AM测量细胞内钙离子浓度。进行体内实验，使用大鼠心肌缺血/再灌注（I/R）模型，通过免疫荧光染色检测心肌中IP3R和SERCA2a的表达。
体外实验结果显示，褪黑素可诱导心肌细胞中的ERK1激活以抵抗H/R，而这被PD98059（ERK1抑制剂）所抑制。结果表明，褪黑素可抑制心肌细胞凋亡，并改善心肌细胞抵抗H/R时的肌动蛋白丝组织，因为这两者均可被PD98059逆转。褪黑素被证明可减少钙超载，进而通过ERK1途径抑制心肌细胞抵抗H/R时的IP3R表达并促进SERCA2a表达。褪黑素可诱导心肌中较低的IP3R表达和较高的SERCA2a表达，而这被PD98059逆转。
褪黑素诱导的抗再灌注损伤心脏保护作用至少部分是通过调节IP3R和SERCA2a，经激活ERK1来维持细胞内钙稳态实现的。
